you can find a free demo version of rhinoceros at
http://www.rhino3d.com
it's very easy to learn compared to other programs (like lightwave, aaargh it takes years until you've mastered that program :s) because all commands are clearly shown in the interface)
if you know to speak dutch and you want more info about any 3d program there's also this forum
http://3dforum.thesquad.nl (as this is a forum that's only for dutch languaged people and not specially about DB I think this is no concurrention for this forum). My name on that other forum is
bernardfrancois.
There's also some free modelling program that's also quite easy (but hasn't very much features) and it's called
spatch. In that program there's only one modelling technique in which you have to draw surface patches.
Here's a render of an axe I modelled in spatch:
http://www.ping.be/groen/bernardfrancois/3d/axe.htm
This is a book I modelled in spatch. The result might look not very satisfying but there were some errors in my model.
http://www.ping.be/groen/bernardfrancois/3d/book.htm
Here's an other render of an spatch object
http://www.ping.be/groen/bernardfrancois/3d/ice.htm
spatch isn't very good to re-model an existing object; it's better when you just imagine something while modelling
in this case I wanted to make a horse chess piece but it looked more like a dog I guess (or is it a horse after all? I still don't know lol)
http://www.ping.be/groen/bernardfrancois/3d/horsedog.htm
With rhino3d you can make very detailed models. Like this one, in which I made a 3d version of my pc speakers
http://www.ping.be/groen/bernardfrancois/3d/boxen.htm
